1. Field of the Invention
This invention is related in general to the field of convertible sofas and chairs and, in particular, to a mechanism that facilitates the unfolding of a sofa or a chair into a flat bed and the re-folding thereof.
2. Description of the Prior Art
Sofas and chairs that convert into beds have long been popular in homes throughout the world. The convertible unit that provides a place to sit by day and a place to sleep by night is often a necessity in small apartments, especially the one-room dwellings commonly referred to as efficiency apartments. Even larger homes often utilize convertible sofas as "pop-out" guest bedrooms.
Over the years inventors have developed a wide variety of these sofas and chairs that convert to beds and many different mechanisms for accomplishing the conversion. In U.S. Pat. No. 482,262 (1892), for example, Miller describes what was probably the first modern sofa bed. The seat and back portions of the sofa are hinged to the frame to permit the former to slide forward and the latter to pivot to a horizontal position next to the seat. Thus, the two portions may be moved to the desired position to obtain either a sofa or a bed.
U.S. Pat. No. 1,062,337 to Kampe (1913) discloses a collapsible frame for a divanette, whereby the seat and back portions can be folded open to provide a flat bed area. A system of levers attached to the frame enables a user to easily close and open the divanette.
U.S. Pat. No. 2,291,677 to Bank (1942) shows another bed-couch combination having two substantially equal portions constituting the seat and back of a couch. When needed as a bed, the back can be reclined to a horizontal position to form a flat bed surface. A system of springs linking the portions to the supporting frame facilitates the lifting of the various parts to change from one form to the other.
Another sofa bed is described in U.S. Pat. No. 3,002,198 to Kaiser (1961). Three side-by-side panels, hinged to one another along their length, may be positioned on a horizontal frame to form a bed, or folded to make a sofa. Two of the panels fold back to back to create the vertical portion of the sofa, while the third panel slides horizontally to form the seat. Again, various springs aid the process of folding and unfolding the sofa.
U.S. Pat. No. 3,107,363 to Simmons (1963) discloses a hinge mechanism designed to permit the back portion of a sofa bed to be perfectly aligned with the seat portion when the two are in horizontal position. The patent is directed at the specific structure constituting the hinge mechanism, providing a pivot point approximately at the same height as the frame of the sofa bed. This enables the construction of a sofa bed that does not expose the pivot points in its open position.
U.S. Pat. No. 4,205,405 to Hagney (1980) describes another convertible couch comprising a back portion hinged to a seat portion that slide forward to form a bed. Arm-rest pieces are used to fill the gap that exists between the seat and the back when they are positioned horizontally.
Finally, U.S. Pat. No. 4,543,675 to Shrock (1985) teaches the construction of a convertible seat for a vehicle. A system of scissor levers anchored to the frame of the seat permit its conversion to a full-size bed by mechanically rearranging three panels from a seat-back configuration to a horizontal plane.
Many available sofa-beds convert by means of complex mechanisms that often require much strength and are difficult to manipulate and that, because of the arrangement of the numerous parts, at times produce an uncomfortable sleeping surface. Many are further complicated by having a separate mattress actually folded into the unit or by requiring the removal of cushions and pillows before the unit can be folded out. The result is that the process of converting a sofa-bed from one configuration to the other is usually cumbersome and difficult to accomplish by one person alone, especially the operation of folding the open bed into a sofa. Therefore,, there exists a need for a mechanism that facilitates this operation, so that it can be easily accomplished with minimum effort by a person alone.